Modular buildings are an old concept. For example, U.S. Pat. No. 3,710,534, granted Jan. 16, 1973, to John O. McNamara, Jr., discloses constructing a building from a plurality of right angle modules, connected together to form rectangular shaped cells. U.S. Pat. No. 3,714,304, granted Jan. 30, 1973, to John W. Carner and Frank B. Anderson, discloses constructing a building from modules which are cast with a ceiling structure and depending wall structures, but are open at the bottom. The modules are placed side-by-side horizontally and are stacked vertically to form a building. U.S. Pat. No. 3,733,763, granted May 22, 1973 to Ernest R. Drucker discloses constructing a building from modules which are separate units of the building, e.g. separate apartments. U.S. Pat. No. 4,136,492, granted Jan. 30, 1979 to John H. Willingham, discloses constructing a modular building from T-shaped modules.
It is also known to construct multi-story circular buildings composed of a plurality of rooms or units positioned about a center shaft or chamber. For example, the aforementioned U.S. Pat. No. 4,136,492 discloses (FIGS. 40 and 41) locating a plurality of rooms about a center stairwell. The rooms are constructed from T-shaped modules, each of which has a flat roof, a flat floor and flat sidewalls. The sidewalls extend radially, so each room narrows down from its outside end to its inside end. The aforementioned U.S. Pat. Nos. 3,714,304 and 3,733,763 also discloses buildings composed of units positioned about a center space. Additional buildings of this general type are disclosed by the following U.S. Pat. Nos.: 1,709,914, granted Apr. 23, 1929 to Elmer R. Klanke; 3,295,265, granted Jan. 3, 1967 to Naoto Hida; 3,358,407; granted Dec. 19, 1967, to Bruno Konig; 3,419,161, granted Dec. 31, 1968, to Carl H. Hagel; 3,419,162, granted Dec. 31, 1968, to Carl H. Hagel; 3,437,218, granted Apr. 8, 1969 to Carl H. Hagel; and 3,474,918, granted Oct. 28, 1969, to Antonius J. M. F. Postmes and Cornelis M. Wennekes.